If the rollercoaster speed is 90 kmh at point 1 find the spe

If the roller-coaster speed is 90 km/h at point 1, find the speed at point 2. Neglect friction. The height difference between the two points is 30 m.

Using energy conservation from point 1 to point 2

1/2 mv1^2 = mgh + 1/2mv2^2

all masses are cancel each other

[v1 = 90 km/h = (90 x 1000) / (60 x 60) = 25 m/s]

.5 x (25)^2 = ((9.8 x (15 + 15)) + (.5 x v2^2)

v2 = 6.08 m/s = 21.8 km/h